1. Field of the Invention
The present invention relates to replacement heart valves. More specifically, the invention relates to tissue- or simulated tissue-based replacement heart valves.
2. Description of the Related Art
Human heart valves, which include the aortic, pulmonary, mitral and tricuspid valves, function essentially as one-way valves operating in synchronization with the pumping heart. The valves allow blood to flow in a downstream direction, but block blood from flowing in an upstream direction. Diseased heart valves exhibit impairments such as narrowing of the valve or regurgitation. Such impairments reduce the heart's blood-pumping efficiency and can be a debilitating and life threatening condition. For example, valve insufficiency can lead to conditions such as heart hypertrophy and dilation of the ventricle. Thus, extensive efforts have been made to develop methods and apparatus to repair or replace impaired heart valves.
Prostheses exist to correct problems associated with impaired heart valves. For example, mechanical and tissue-based heart valve prostheses can be used to replace impaired native heart valves. More recently, substantial effort has been dedicated to developing replacement heart valves, particularly tissue-based replacement heart valves, that can be delivered with less trauma to the patient than through open heart surgery. Replacement valves are being designed to be delivered through minimally invasive procedures and even percutaneous procedures. Such replacement valves often include a tissue-based valve body that is connected to an expandable stent that is then delivered to the native valve's annulus.
Development of replacement heart valves that can be compacted for delivery and then controllably expanded for controlled placement has proven to be particularly challenging. Further, durability concerns, particularly with tissue-based replacement valves, are at the forefront. For example, tissue-based valves typically include components that are sewn together, and such seams can be sources of stress concentrations, particularly when relatively thin tissue is used.